Checking your URL I got an error, because the path you provided misses the “//” in http:// : <meta property=“og:image” content=“http:omprakash.org/images/logo_fb.jpg”/>
Same thing for the donations page. Once you have fixed this, it should work correctly.
Thank you. I will try that. I think I found the cause of the problem. Pages where the like button was pressed before the image was provided use the original image found by Facebook. All the others use the default image. Is there a way to clear Facebook’s memory of this?